This is a tricky one to answer without any further understanding of the typical scenarios and your users needs. From a user interface perspective there are lots of ways to display this information: drop down lists/multiple selects/tabs/simple links etc. See: http://ui-patterns.com/
I would focus more on research into the users/tasks, some point to consider could include:
Does all the information have to be presented on the same page? Could it be broken down into steps?
Consider whether all people need to see all tabs? Is there any logic to how different user types engage with the system? This could provide you with the opportunity to tailor the view to the user. Or allow the user to tailor which information they want to see first?
Thinking about the topic "people and company details" - I would hypothesise that there are ways to group these 20 tabs/links/tasks together. Typically you may see information grouped into sections such as "personal information" "organisation details".